Bluma Wulfovna Zeigarnik (1901 – 1988) was a Soviet psychologist and psychiatrist. She first studied the phenomenon after her professor noticed that a waiter had better recollections of still unpaid orders. However, after the completion of the task – after everyone had paid – he was unable to remember any more details of the orders!

The effect can explained by looking at Lewin’s field theory: a task that has already been started establishes a task-specific tension, which improves cognitive access to any relevant information.

This tension that has been established is relieved upon successful completion of the task. If the task is interrupted, any reduction of tension is impeded. With continuous tension, the relevant information is becomes more accessible and more easily remembered.

The Zeigarnik effect suggests that students who temporarily stop their studies, during which they do unrelated activities (such as studying unrelated subjects or playing games), will remember material better than students who complete study sessions without a break (Zeigarnik, 1927; McKinney 1935).

Takeaways for Decision-Makers

If you’re looking to promote further consumption of material you’re writing, focus on it being incomplete, such as the use of an ellipsis instead of a full stop in an email header. Our natural desire to complete a task will result in the deeper content being read. Don’t disclose all of the value of your work right at the beginning.

Break down consumed content into smaller parts, making portions easier to digest and also to offer up the view that readers are ‘not yet done’.

Think about how to best take advantage of the user’s state of mind after having completed the ‘task’. Are there things they’d be more likely, able or mentally-free to do at the end of the task that they’d not be able to, prior to completion?